1. Field of the Invention
The present invention relates to a heat shield configuration for protecting a supporting structure against a hot fluid. The heat shield configuration has an inner liner formed of a heat resistant material and is composed of plate-shaped heat shield elements resistant to high temperatures. The heat shield elements are disposed next to one another with gaps in-between. The heat shield elements cover the entire area of the supporting structure.
Such a heat shield configuration is known, for example, from European Patent Application EP 0 224 817 A. This publication proposes that the heat shield configuration have an inner lining consisting of a heat-resistant material. The inner lining is composed of plate-shaped heat-shield elements resistant to high temperatures that are disposed next to one another so as to cover the entire area, with gaps being left. The individual heat-shield elements are anchored to the supporting structure by bolts so as to be thermally movable.
The individual heat-shield elements are configured in the manner of a mushroom with a cap part and a stem part, the cap part being a plane or three-dimensional polygonal plate body.
Such heat shield configurations for protecting a supporting structure against a hot fluid, with an inner lining consisting of heat-resistant material, are used, in particular, for constructing a combustion chamber, particularly for gas turbines. An atmosphere attacking the inner lining is generated in the combustion chamber of a gas turbine during the combustion operation. While a gas turbine is operating, the inner lining is exposed to a relatively high temperature. In addition to the thermal load on the inner lining, structural changes to the heat-shield elements may occur on account of the temperature and gas atmosphere. The individual heat-shield elements of a heat shield configuration also undergo dynamic loading due to vibrations that arise in a combustion chamber of a gas turbine during the combustion operation. In order to reduce the thermal load on the inner lining and consequently on the individual heat-shield elements, it is known to cool the heat-shield elements in relation to the combustion-chamber wall. The coolant flows around the underside of the heat-shield elements and flows through the gaps between the individual heat-shield elements into the combustion chamber, the gaps ensuring that the heat-shield elements are cooled with regard to the hot gas. The introduction of cooling air into the combustion chamber leads to an increased nitrogen oxide emission, since the combustion takes place with an excess of air. However, the emission of nitrogen oxides is undesirable. If the gas turbine is to be operated at increased temperatures, this entails an increased coolant consumption.
Published, Non-Prosecuted German Patent Application DE 41 14 768 Al describes a heat shield on a structure, in particular a flame tube for a gas turbine. The structure carries hot gases and has a supporting wall, and the heat shield consists of a multiplicity of bricks. The bricks are disposed next to one another so as to cover essentially the entire area and are each fastened to the supporting wall by at least one associated holder. Each brick has a cold side facing the supporting wall, a hot side facing away from the supporting wall and at least two flanks which connect the cold side to the hot side. Each associated holder is fastened to the supporting wall and contains at least two interacting clamp lugs which engage the respectively associated brick on the cold side between the flanks. Each holder consists preferably of sheet metal and each brick of a ceramic.
U.S. Pat. No. 5,333,433 teaches a sealing configuration for sealing an opening between the combustion chamber stone and a supporting structure of a combustion chamber. The combustion chamber stone includes a fireproof interior lining of a part of a circular combustion chamber. The combustion chamber stone is placed with a perpendicularly bent rim in an opening of the supporting structure and fixed with a bolt. Between the combustion chamber stone and the supporting structure remains an opening. Through the opening cooling air which is fed through bores in the supporting structure towards the interior side of the combustion chamber stones can escape. To prevent a cooling air loss a sealing configuration is provided. The combustion chamber stone is made completely and homogeneously of a fireproof ceramic.